In the above described technical field, the generator may be air cooled with the air being drawn out of the generator by two fans.
A reason for having two cooling fans is redundancy, i.e. in case of one cooling fan failing the other can still run and provide the cooling power required by the generator. In most operational conditions with low ambient temperature, one cooling fan alone is able to supply the cooling capacity necessary for full power production.
One inconvenient of the above describe layout is due to the short outlet ducting of the fans, which is necessarily determined by the limited space available in the nacelle. This causes, especially during storms and high cross wind periods, rainwater to enter the fans and consequently the generator. Water entering the generator should be prevented to avoid corrosion and the consequent damages, in which the generator would incur.
It is therefore desirable to provide in the nacelle a draining pipe between each of the fans and the external environment, to ensure a complete drainage of any water entering the fan and prevent the ingress of rainwater into the generator.
At the same it is however further desirable that such draining pipe does not allow dirty air from the external environment to reach the fans and the generator. The external environment may for example include dusts or other pollutants potentially dangerous for the fans and electrical generator.
Scope of the present is to provide a nacelle satisfying the above positive requirements, i.e. the draining of water from the cooling fans in the nacelle, and at the same time avoiding the described inconveniences, i.e. avoiding the entering of dirty air in the nacelle through the water draining system.